But some of Mr. Macron’s isolation is also a function of his favored self-image as a solitary warrior, creating a stark choice between himself and the French far right for next May’s elections for the European Parliament, which are shaping up as a battle between the forces of integration and fragmentation on the Continent.

Even at home, Mr. Macron has some persuading to do. This week, for the first time in the race, a poll showed the president’s political movement, La République en Marche, or Republic on the Move, falling slightly behind the anti-Europe, far-right Rassemblement National, formerly known as the National Front, in the race for European Parliament seats.

Several analysts see a direct link between the increasing disaffection of French citizens with their leader, and his isolation in the world. Unlike Ms. Merkel, who for most of her term was quite popular and at times even beloved at home, Mr. Macron’s youthful appeal waned as he pushed through one reform after another, which have yet to yield much economic improvement for those people who fear being left behind.

“He has been insensitive to the kinds of popular concerns that make people feel they are drowning,” said Pascal Perrineau, a political-science professor at Sciences Po.

Marielle de Sarnez, a Macron ally and chairwoman of the French Parliament’s foreign affairs committee, said the French president was not isolated, but that Europe’s populists were “responding to the people’s fears, that we and President Macron have to take into account.’’

“It is not a lost fight,’’ she added. ‘‘But it’s our responsibility to take into account the fears of the people and identify, for instance, the frontiers. And he’s got a very important role in that. The European peoples, it is up to us to pull them together.”

But Mr. Macron himself has become a divisive figure for many in France who fear a widening gap between the haves and have-nots, and between tradition and change.